Metadata is a set of data that describes the organization of user data or other metadata on a data storage partition or a file system volume. Preserving file system metadata is critical to the operation of modern file systems and helps ensure that user data written to the file system volume will be accessible when requested. However, occasionally, end user workloads, end user mistakes, malicious operations, or bugs in a file system driver may cause improper behavior that can result in metadata corruption, especially in unstable file systems. It is possible to encounter metadata corruptions even in mature file systems.
When a file system's metadata becomes corrupted, special tools such as the “fsck” (file system consistency check) system utility (in Unix-like operating systems) or backup/restore software are often used to attempt to recover the file system data. However, using the fsck utility is a very time-consuming operation and cannot guarantee that a corrupted file system's data will be recovered. Furthermore, such tools can be used only when the file system is in an unmounted (e.g., offline) state. As such, preventing metadata corruption is a more beneficial approach than detecting corruption and attempting to recover corrupted data.